RFR (XS) 8199012: JVM crash during LevelDB JNI access

[Thomas Stüfe]

Looks obvious and fine.

Thanks, Thomas

On Wed, Mar 7, 2018 at 12:31 AM, David Holmes <david.holmes at oracle.com>
wrote:

> webrev: http://cr.openjdk.java.net/~dholmes/8199012/webrev/
> bug: https://bugs.openjdk.java.net/browse/JDK-8199012
>
> JNI DetachCurrentThread is defined as a no-op if called by a thread that
> is not attached. But the check for that was occurring after we called
> VM_Exit::block_if_vm_exited(). If the thread was not in fact attached then
> we have a NULL current thread and that can cause in crash in
> VM_Exit::block_if_vm_exited() if we actually need to block - which explains
> the scenario reported in the bug.
>
> Simple, obvious, fix is to do the "not attached" check first.
>
> Testing:
>   - Mach5 CI equivalent testing (tier1/2)
>   - internal JNI tests
>
> I marked this noreg-hard as a regression test is difficult to set up due
> to the need to coordinate with a VM shutdown.
>
> Thanks,
> David
>